In some sailing areas, such as the United Kingdom, a marina has floating pontoons from which extend floating fingers. Generally the fingers are spaced apart such that two craft can occupy the space between, each craft being adjacent and attached to a finger. Generally the fingers include decking allowing users to walk on the finger and access the attached craft, flotation units provided beneath the decking, and mooring points allowing the securing of ropes to attach the adjacent craft. To enter the berth, the user has to approach parallel to the pontoon and then make a right-angle turn into the berth. This manoeuvre can present some difficulty, especially where there is a strong wind or tidal current across the berth, or if the user lacks experience, and it is quite common for a craft entering or leaving a berth to make contact with the neighbouring vessel or with the corner of the finger. Such contact is frequently sufficiently heavy to case damage. Also, in an attempt to minimise such occurrences marina operators may increase the spacing between fingers; this makes maneuvering simpler but is wasteful of valuable mooring space.
In other sailing waters, such as the Mediterranean, small craft commonly berth bows-to or stern-to a floating pontoon or a fixed dock. In this case, the craft must approach at right angles to the pontoon or dock into a clear space between vessels already berthed. The leading end (bows or stern) must be made fast to the pontoon or dock, and the opposite end is secured to permanent mooring ropes with pick-up buoys, or by dropping an anchor during the approach. Here again, the manoeuvre can be difficult in cross-wind or cross-tide conditions, especially if made into a space which is just sufficiently wide, and damaging collisions can occur.
It will be appreciated that floating pontoons are generally used wherever there is a significant tidal range, while fixed docks are commonly used where tidal range is small, e.g. the Mediterranean or the Baltic. For simplicity, the term “pontoon” will be used herein to include both.